Display device

ABSTRACT

A display device that includes a display panel having a first substrate, a second substrate, and a light-emitting element layer. The light emitting layer is disposed between the first and second substrates and is configured to emit light in a direction toward the second substrate. A first sound generator is disposed on a first surface of the first substrate and is configured to vibrate the display panel to output a first sound. A first heat dissipation film is disposed between the first substrate and the first sound generator.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/724,884 filed on Dec. 23, 2019, which claims priority under 35 U.S.C§ 119 to Korean Patent Application No. 10-2018-0170555, filed on Dec.27, 2018, in the Korean Intellectual Property Office (KIPO), thedisclosures of which are incorporated by reference in their entiretiesherein.

1. TECHNICAL FIELD

The present disclosure relates to a display device.

2. DISCUSSION OF RELATED ART

The demand for display devices that are configured to display images hasincreased and diversified as the information society has developed. Forexample, display devices have been included in a variety of electronicdevices including smart phones, digital cameras, notebook computers,navigation devices, smart televisions (TV), etc. Examples of displaydevices include flat panel display devices, such as a liquid crystaldisplay (LCD) device, a field emission display (FED) device, an organiclight-emitting diode (OLED) display device, etc.

A display device may include a display panel for displaying an image anda speaker for providing sound. Sound may preferably be output from thespeaker in the front direction of the display device for improved soundquality. However, due to the limited space of display devices, thespeaker is often disposed at the rear or on one side of the displaypanel. This results in the display device outputting a low qualitysound.

SUMMARY

Exemplary embodiments of the present disclosure may provide a displaydevice capable of improving the quality of sound by causing a displaypanel to vibrate and thereby outputting sound in the front directionthereof.

According to an exemplary embodiment of the present inventive concepts,a display device includes a display panel having a first substrate, asecond substrate, and a light-emitting element layer. The light-emittinglayer is disposed between the first and second substrates and isconfigured to emit light in a direction toward the second substrate. Afirst sound generator is disposed on a first surface of the firstsubstrate and is configured to vibrate the display panel to output afirst sound. A first heat dissipation film is disposed between the firstsubstrate and the first sound generator.

According to another exemplary embodiment of the present inventiveconcepts, a display device includes a display panel. A first soundgenerator is disposed on a first surface of the display panel and isconfigured to vibrate the display panel to output a sound. A first heatdissipation film is disposed between the display panel and the firstsound generator. The first heat dissipation film includes a holeoverlapping with the first sound generator.

According to a further exemplary embodiment of the present inventiveconcepts, a display device includes a display panel. The display panelincludes a first substrate, a second substrate, a light-emitting elementlayer disposed between the first and second substrates, and a heatdissipation film disposed on the first substrate. The heat dissipationfilm includes a heat dissipation layer and at least one vibrationtransmission layer. At least one sound generator is disposed on the heatdissipation film and is configured to vibrate the first substratethrough the at least one vibration transmission layer of the heatdissipation film to output a sound. The display panel serves as adiaphragm for generating the sound.

According to the aforementioned and other exemplary embodiments of thepresent disclosure, since a first sound generator outputs first soundusing a display panel as a diaphragm, sound can be output in the frontdirection of a display device, and as a result, the quality of the soundcan be improved. Also, due to the first sound generator, a speaker canbe omitted from the rear or a side of the display panel.

In addition, since multiple sound generators are provided on one surfaceof the display panel, multi-channel stereo sound can be provided to auser.

Moreover, since heat dissipating pass holes may be formed on a firstheat dissipation film to overlap with a first sound generator, heatgenerated by the first sound generator can be effectively released bythe heat dissipation pass holes. Accordingly, the influence of the heatgenerated by the first sound generator on the display panel can beminimized by the first heat dissipation film.

Furthermore, since a second heat dissipation film is further disposedbetween the first heat dissipation film and the first sound generator,the heat generated by the first sound generator can be further blockedby the second heat dissipation film and can thus be prevented fromaffecting the display panel.

Other features and exemplary embodiments may be apparent from thefollowing detailed description, the drawings, and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other embodiments and features of the present disclosurewill become more apparent by describing in detail exemplary embodimentsthereof with reference to the attached drawings, in which:

FIG. 1 is a perspective view of a display device according to anexemplary embodiment of the present inventive concepts;

FIG. 2 is an exploded perspective view of the display device of FIG. 1according to an exemplary embodiment of the present inventive concepts;

FIG. 3 is a side view illustrating an exemplary display panel of FIG. 2according to an exemplary embodiment of the present inventive concepts;

FIG. 4 is a cross-sectional view illustrating a display area of thedisplay panel of FIG. 2 according to an exemplary embodiment of thepresent inventive concepts;

FIG. 5 is a bottom view illustrating a display device with flexiblefilms thereof in an unbent orientation according to an exemplaryembodiment of the present inventive concepts;

FIG. 6 is a bottom view illustrating a display device with flexiblefilms thereof in a bent orientation according to an exemplary embodimentof the present inventive concepts;

FIG. 7 is an exploded perspective view illustrating a first soundgenerator according to an exemplary embodiment of the present inventiveconcepts;

FIG. 8 is a cross-sectional view taken along line I-I′ of FIG. 7according to an exemplary embodiment of the present inventive concepts;

FIGS. 9A and 9B are side views illustrating the vibration of a displaypanel caused by the first sound generator of FIGS. 7 and 8 according toan exemplary embodiment of the present inventive concepts;

FIG. 10 is a perspective view illustrating a first sound generatoraccording to an exemplary embodiment of the present inventive concepts;

FIG. 11 is a cross-sectional view of the first sound generator of FIG.10 according to an exemplary embodiment of the present inventiveconcepts;

FIG. 12 is a schematic view illustrating the vibration of a vibrationlayer disposed between first branch electrodes and second branchelectrodes of the first sound generator of FIGS. 10 and 11 according toan exemplary embodiment of the present inventive concepts;

FIGS. 13A and 13B are side views illustrating the vibration of a displaypanel caused by the first sound generator of FIGS. 10 and 11 accordingto an exemplary embodiment of the present inventive concepts;

FIG. 14 is a bottom view of a display device according to anotherexemplary embodiment of the present inventive concepts;

FIG. 15 is a bottom view of a display device according to anotherexemplary embodiment of the present inventive concepts;

FIGS. 16A and 16B are a side view and a bottom view, respectively, of adisplay device according to another exemplary embodiment of the presentinventive concepts;

FIG. 17 is an exploded perspective view illustrating a third soundgenerator according to an exemplary embodiment of the present inventiveconcepts;

FIG. 18 is a bottom view of a display device according to anotherexemplary embodiment of the present inventive concepts;

FIG. 19 is a graph showing the sound pressure levels, at each frequency,of sound generated by sound generators according to an exemplaryembodiment of the present inventive concepts;

FIG. 20 is a side view illustrating an exemplary display panel of FIG. 2according to an exemplary embodiment of the present inventive concepts;

FIGS. 21A through 21E are bottom views illustrating bobbins and heatdissipation pass holes of first sound generators according to exemplaryembodiments of the present inventive concepts;

FIG. 22 is a cross-sectional view taken along line of FIG. 21A accordingto an exemplary embodiment of the present inventive concepts;

FIG. 23 is a cross-sectional view taken along line of FIG. 21A accordingto an exemplary embodiment of the present inventive concepts;

FIG. 24A is a plan view illustrating a first sound generator and asecond heat dissipation film according to an exemplary embodiment of thepresent inventive concepts;

FIGS. 24B and 24C are cross-sectional views taken along line IV-IV′ ofFIG. 24A according to an exemplary embodiment of the present inventiveconcepts;

FIG. 25 is a cross-sectional view illustrating a first sound generatorand a first heat dissipation film according to an exemplary embodimentof the present inventive concepts;

FIG. 26A is a plan view illustrating a first sound generator and a heatdissipation layer of a first heat dissipation film according to anexemplary embodiment of the present inventive concepts;

FIGS. 26B, 27, and 28 are cross-sectional views taken along line V-V′ ofFIG. 26A according to exemplary embodiments of the present inventiveconcepts;

FIG. 29A is a plan view illustrating an exemplary first sound generator,an exemplary second sound generator, and an exemplary heat dissipationlayer of an exemplary first heat dissipation film according to anexemplary embodiment of the present inventive concepts;

FIG. 29B is a cross-sectional view taken along line VI-VI′ of FIG. 29Aaccording to an exemplary embodiment of the present inventive concepts;

FIGS. 30A and 30B are a side view and a bottom view, respectively, of adisplay device according to another exemplary embodiment of the presentinventive concepts;

FIG. 31 is a bottom view of a display device according to anotherexemplary embodiment of the present inventive concepts;

FIG. 32 is a bottom view of a display device according to anotherexemplary embodiment of the present inventive concepts; and

FIG. 33 is a bottom view of a display device according to anotherexemplary embodiment of the present inventive concepts.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

The present invention will now be described more fully hereinafter withreference to the accompanying drawings, in which exemplary embodimentsof the invention are shown. This invention may, however, be embodied indifferent forms and should not be construed as limited to the exemplaryembodiments set forth herein. The same reference numbers indicate thesame components throughout the specification. In the attached figures,the thickness of layers and regions may be exaggerated for clarity.

It will also be understood that when a layer is referred to as being“on” another layer or substrate, it can be directly on the other layeror substrate, or intervening layers may also be present. In contrast,when an element is referred to as being “directly on” another element,there are no intervening elements present.

Hereinafter, embodiments of the present invention will be described withreference to the attached drawings.

Referring to FIGS. 1 through 3, a display device 10 will hereinafter bedescribed as being, for example, an organic light-emitting diode (OLED)display device. However, exemplary embodiments of the present inventiveconcepts are not limited thereto. For example, in certain exemplaryembodiments, the display device 10 may be a micro light-emitting diode(LED) display device or an inorganic LED display device using aninorganic semiconductor (e.g., inorganic LEDs).

The display device 10 may include a cover frame 100, a display panel110, source driving circuits 121, flexible films 122, source circuitboards 140, flexible cables 150, a control circuit board 160, and atiming control circuit 170.

The terms “above”, “top”, and “top surface”, as used herein, denote adirection in which a second substrate 112 of the display panel 110 isdisposed with respect to a first substrate 111 of the display panel 110,e.g., a Z-axis direction. The terms “below”, “bottom”, and “bottomsurface”, as used herein, denote a direction in which the firstsubstrate 111 is disposed with respect to the second substrate 112,i.e., the direction opposite to the Z-axis direction. The terms “left”,“right”, “upper”, and “lower”, as used herein, denote the respectivedirections as viewed from above the display panel 110. For example, theterm “left” denotes an X-axis direction, the term “right” denotes thedirection opposite to the X-axis direction, the term “lower” may denotea Y-axis direction, and the term “upper” may denote the directionopposite to the Y-axis direction.

The cover frame 100 may be disposed to cover the edges of the displaypanel 110. The cover frame 100 may cover a non-display area of thedisplay panel 110. The cover frame 100 may not cover a display area ofthe display panel 110. Specifically, as illustrated in FIG. 2, the coverframe 100 may include upper and lower covers 101 and 102. In anexemplary embodiment, the upper cover 101 may cover the edges of the topsurface of the display panel 110, and the lower cover 102 may cover thebottom surface and the side surfaces of the display panel 110. The upperand lower covers 101 and 102 may be coupled to each other via a fixingmember. The upper and lower covers 101 and 102 may be formed of plasticor a metal or may include both plastic and a metal.

In an exemplary embodiment, the display panel 110 may have a rectangularshape in a plan view. For example, in a plan view, the display panel 110may have a rectangular shape having its relatively longer sidesextending in a first direction (e.g., the X-axis direction) and itsrelatively shorter sides extending in a second direction (e.g., theY-axis direction). The corners where the long sides and the short sidesmeet may be right-angled or rounded. However, the planar shape of thedisplay panel 110 is not particularly limited. Accordingly, in exemplaryembodiments the display panel 110 may be formed in various other shapessuch as a polygonal shape other than a rectangular shape, a circularshape, or an elliptical shape.

The exemplary embodiment shown in FIG. 2 includes a display panel 110that is flat. However, exemplary embodiments of the present inventiveconcepts are not limited thereto and the display panel 110 may be formedto have a bend with a predetermined curvature.

The display panel 110 may include the first and second substrates 111and 112. The first and second substrates 111 and 112 may be formed to berigid or flexible. In exemplary embodiments, the first substrate 111 maybe formed of glass or plastic, and the second substrate 112 may beformed of glass, plastic, an encapsulation film, or a barrier film. Forexample, each of the first and second substrates 111 and 112 may includeplastic such as polyethersulphone (PES), polyacrylate (PA), polyarylate(PAR), polyetherimide (PEI), polyethylene naphthalate (PEN),polyethylene terephthalate (PET), polyphenylene sulfide (PPS),polyallylate, polyimide (PI), polycarbonate (PC), cellulose triacetate(CAT), cellulose acetate propionate (CAP), or a combination thereof. Forexample, each of the first and second substrates 111 and 112 may includean encapsulation film or a barrier film in which a plurality ofinorganic films are stacked.

As shown in FIG. 3, the display panel 110 may include a display layer113 disposed between the first and second substrates 111 and 112. Asshown in FIG. 4, the display layer 113 may include a thin-filmtransistor (TFT) layer TFTL, a light-emitting element layer EML, athin-film encapsulation layer (TFEL) 305, a filler member FL, a lightwavelength conversion layer QDL, and a color filter layer CFL. In anexemplary embodiment, the first substrate 111 may be a TFT substrate onwhich the TFT layer TFTL, the light-emitting element layer EML, and theTFEL 305 are formed. The second substrate 112 may be a color filtersubstrate on which the light wavelength conversion layer QDL and thecolor filter layer CFL are formed. The filler member FL may be disposedbetween the TFEL 305 on the first substrate 111 and the light wavelengthconversion layer QDL on the second substrate 112. The display layer 113will be described later in further detail with reference to FIG. 4.

Since the first substrate 111 may have a larger size than the secondsubstrate 112, one side of the first substrate 111 may not be covered bythe second substrate 112, but may be exposed. The flexible films 122 maybe attached to a part of the first substrate 111 that is not covered bythe second substrate 112. In an exemplary embodiment, the flexible films122 may be tape carrier packages or chip-on-films. The flexible films122 may be attached on the first substrate 111 via an anisotropicconductive film using a tape automated bonding (TAB) method, and as aresult, the source driving circuits 121 may be connected to data lines.

The flexible films 122 may be bendable. For example, the flexible films122 may be bent toward the bottom surface of the first substrate 111. Asillustrated in the exemplary embodiment shown in FIG. 6, the sourcecircuit boards 140, the flexible cables 150, and the control circuitboard 160 may be disposed on the bottom surface of the first substrate111.

In the exemplary embodiment shown in FIG. 2, eight flexible films 122are attached on the first substrate 111 of the display panel 110.However, the number of flexible films 122 provided is not particularlylimited.

The source driving circuits 121 may be attached on the flexible films122. The source driving circuits 121 may be formed as integratedcircuits (ICs). The source driving circuits 121 may convert digitalvideo data into analog data voltages in accordance with source controlsignals received from the timing control circuit 170. The source drivingcircuits 121 may provide the analog data voltages to the data lines ofthe display panel 110 via the flexible films 122.

First sides of the flexible films 122 may be attached on the firstsubstrate 111 of the display panel 110, and second sides of the flexiblefilms 122 may be attached on the source circuit boards 140. The sourcecircuit boards 140 may be connected to the control circuit board 160 viathe flexible cables 150. The source circuit boards 140 may include firstconnectors 151 for connecting the source circuit boards 140 to theflexible cables 150. In an exemplary embodiment, the source circuitboards 140 may be printed circuit boards (PCBs) or flexible PCBs(FPCBs).

The control circuit board 160 may be connected to the source circuitboards 140 via the flexible cables 150. To this end, the control circuitboard 160 may include second connectors 152 for connecting the controlcircuit board 160 to the flexible cables 150. The control circuit board160 may be a PCB or an FPCB.

In the exemplary embodiment illustrated in FIG. 2, four flexible cables150 are provided to connect the source circuit boards 140 and thecontrol circuit board 160. However, the number of flexible cables 150provided is not particularly limited. The exemplary embodimentillustrated in FIG. 2 has two source circuit boards 140. However, thenumber of source circuit boards 140 provided is not particularlylimited.

The timing control circuit 170 may be attached on the control circuitboard 160. The timing control circuit 170 may be formed as an IC. Thetiming control circuit 170 may receive digital video data and timingsignals from a system-on-chip and may generate source control signalsfor controlling the timings of the source driving circuits 121 inaccordance with the timing signals.

The system-on-chip may be mounted on a system circuit board that isconnected to the control circuit board 160 via a flexible cable and maybe formed as an IC. The system-on-chip may be a processor of a smarttelevision (TV), a central processing unit (CPU) a graphics card of acomputer or a notebook computer, an application processor of asmartphone or a tablet personal computer (PC), etc.

A power supply circuit may be additionally attached on the controlcircuit board 160. The power supply circuit may generate voltagesnecessary for driving the display panel 110 based on the main powerapplied from the system circuit board. The power supply circuit maysupply the generated voltages to the display panel 110. For example, thepower supply circuit may generate a high-potential voltage, alow-potential voltage, and an initialization voltage for driving OLEDs.The power supply circuit may supply the high-potential voltage, thelow-potential voltage, and the initialization voltage to the displaypanel 110. The power supply circuit may also generate and supply drivingvoltages for driving the source driving circuits 121 and the timingcontrol circuit 170. The power supply circuit may be formed as an IC.

A first heat dissipation film 130 may be disposed on a surface of thefirst substrate 111 that does not face the second substrate 112. Forexample, the first heat dissipation film 130 may be disposed on thebottom surface of the first substrate 111. A first sound generator 210may be disposed on a surface of the first heat dissipation film 130 thatdoes not face the first substrate ill. For example, the sound generator210 may be disposed on the bottom surface of the first heat dissipationfilm 130.

The first heat dissipation film 130 dissipates heat generated by thevoice coil of the first sound generator 210. In an exemplary embodiment,the first heat dissipation film 130 may include a layer of a metal withhigh thermal conductivity such as graphite, silver (Ag), copper (Cu), oraluminum (Al).

The first heat dissipation film 130 may include a plurality of metallayers formed not in a third direction (e.g., the Z-axis direction), butin the first direction (e.g., the X-axis direction) and the seconddirection (e.g., the Y-axis direction). In this embodiment, heatgenerated by the voice coil of the first sound generator 210 may bediffused in the first direction (e.g., the X-axis direction) and in thesecond direction (e.g., the Y-axis direction) to effectively release theheat. The first direction (e.g., the X-axis direction) may be the widthdirection of the display panel 110, the second direction (e.g., theY-axis direction) may be the height direction of the display panel 110,and the third direction (e.g., the Z-axis direction) may be thethickness direction of the display panel 110. Accordingly, the influenceof heat generated by the first sound generator 210 on the display panel110 may be minimized by the first heat dissipation film 130.

The relative thicknesses D1, D2, D3 of the first heat dissipation film,first substrate and second substrate, respectively, may be configured toprevent heat generated by the first sound generator 210 from affectingthe display panel 110. For example, a thickness D1 of the first heatdissipation film 130 may be greater than a thickness D2 of the firstsubstrate 111 and a thickness D3 of the second substrate 112.

In the exemplary embodiment illustrated in FIG. 3, the first heatdissipation film 130 covers the entire surface of the first substrate111. However, exemplary embodiments of the present inventive conceptsare not limited thereto.

The first heat dissipation film 130 will be described later in furtherdetail with reference to FIGS. 20, 23 through 29, 30A, 30B, and 31through 33.

The first sound generator 210 may be a vibrating device that may beconfigured to cause the display panel 110 to vibrate in the thirddirection (e.g., the Z-axis direction). For example, as illustrated inthe exemplary embodiments shown in FIGS. 7, 8, 9A, and 9B, the firstsound generator 210 may be an exciter configured to generate a magneticforce using a voice coil which causes the display panel 110 to vibrate.As illustrated in the exemplary embodiments shown in FIGS. 10, 11, 12,13A, and 13B, the first sound generator 210 may alternatively be apiezoelectric element that contracts or expands in accordance with avoltage applied thereto and thereby causes the display panel 110 tovibrate. The display panel 110 may serve as a diaphragm for outputtingfirst sound.

As described above, according to the exemplary embodiments of FIGS. 1through 3, the display device 10 may be configured to output a firstsound using the display panel 110 as a diaphragm. Since the displaydevice 10 may output sound in the front direction thereof, the qualityof the outputted sound may be improved. Further, due to the presence ofthe first sound generator 210, a speaker disposed on the bottom surfaceor a side of a typical display device may be omitted.

In the exemplary embodiments shown in FIGS. 1-3, the display device 10may be a mid-size to large-size display device including a plurality ofsource driving circuits 121. However, the present disclosure is notlimited thereto. For example, the display device 10 may be a small-sizedisplay device including only one source driving circuit 121. In thisembodiment, the flexible films 122, the source circuit boards 140, andthe flexible cables 150 may not be provided. The source driving circuit121 and the timing control circuit 170 may be incorporated into a singleIC and may then be attached on a single FPCB or on the second substrate112 of the display panel 110. Examples of a mid-size to large-sizedisplay device include a monitor, a TV, etc. Examples of a small-sizedisplay device include a smartphone, a tablet PC, etc.

FIG. 4 is a cross-sectional view illustrating an exemplary display areaof an exemplary display panel.

Referring to FIG. 4, a display panel 110 may include a first substrate111, a second substrate 112, a TFT layer TFTL, a light-emitting elementlayer EML, a TFEL 305, a filler member FL, a wavelength conversion layerQDL, and a color filter layer CFL.

A buffer film 302 may be formed on a surface of the first substrate 111that faces the second substrate 112. The buffer film 302 may be formedon the first substrate 111 to protect TFTs 335 and light-emittingelements against moisture penetrating the first substrate 111, which maybe susceptible to moisture. The buffer film 302 may include a pluralityof inorganic films that are alternately stacked. For example, the bufferfilm 302 may be formed as a multilayer film in which a silicon oxide(SiOx) film, a silicon nitride (SiNx) film, and/or a silicon oxynitride(SiON) film are alternately stacked. The buffer film 302 may not beprovided.

The TFT layer TFTL is formed on the buffer film 302. The TFT layer TFTLincludes TFTs 335, a gate insulating film 336, an interlayer insulatingfilm 337, a passivation film 338, and a planarization film 339.

The TFTs 335 are formed on the buffer film 302. Each of the TFTs 335 mayinclude an active layer 331, a gate electrode 332, a source electrode333, and a drain electrode 334. The exemplary embodiment shown in FIG. 4includes TFTs 335 having a top gate structure in which the gateelectrode 332 is disposed above the active layer 331. However, exemplaryembodiments of the present inventive concepts are not limited thereto.The TFTs 335 may have a bottom gate structure in which the gateelectrode 332 is disposed below the active layer 331 or a double gatestructure in which the gate electrode is disposed both above and belowthe active layer.

The active layer 331 may be formed on the buffer film 302. The activelayer 331 may be formed of a silicon-based semiconductor material or anoxide-based semiconductor material. A light-shielding layer for blockingexternal light incident on the active layer 331 may be formed betweenthe buffer layer and the active layer.

A gate insulating film 336 may be formed on the active layer 331. Thegate insulating film 316 may be formed as an inorganic film such as, forexample, a silicon oxide film, a silicon nitride film, or a multilayerfilm thereof.

The gate electrode 332 and a gate line may be formed on the gateinsulating film 316. The gate electrode 332 and the gate line may beformed as single- or multilayer films using molybdenum (Mo), Al,chromium (Cr), gold (Au), titanium (Ti), Ni, neodymium (Nd), Cu, or analloy thereof.

The interlayer insulating film 337 may be formed on the gate electrode332 and the gate line. The interlayer insulating film 337 may be formedas an inorganic film such as, for example, a silicon oxide film, asilicon nitride film, or a multilayer film thereof.

The source electrode 333, the drain electrode 334, and a data line maybe formed on the interlayer insulating film 337. The source electrode333 and the drain electrode 334 may be connected to the active layer 331through contact holes penetrating the gate insulating film 336 and theinterlayer insulating film 337. The source electrode 333, the drainelectrode 334, and the data line may be formed as a single layer film ormultilayer films using Mo, Al, Cr, Au, Ti, Ni, Nd, Cu, or an alloythereof.

The passivation film 338 may be formed on the source electrode 333, thedrain electrode 334, and the data line to insulate the TFTs 335. Thepassivation film 338 may be formed as an inorganic film such as, forexample, a silicon oxide film, a silicon nitride film, or a multilayerfilm thereof.

The planarization film 339 may be formed on the passivation film 338 toplanarize height differences formed by the TFTs 335. The planarizationfilm 339 may be formed as an organic film using an acrylic resin, anepoxy resin, a phenolic resin, a polyamide resin, or a polyimide resin.

The light-emitting element layer EML may be formed on the TFT layerTFTL. The light-emitting element layer EML may include light-emittingelements and a pixel defining film 344.

The light-emitting elements and the pixel defining film 344 may beformed on the planarization film 339. In an exemplary embodiment, thelight-emitting elements may be OLEDs. In this embodiment, each of thelight-emitting elements may include an anode electrode 341, alight-emitting layer 342, and a cathode electrode 343.

The anode electrode 341 may be formed on the planarization film 339. Theanode electrode 341 may be connected to the source electrode 333 througha contact hole penetrating the passivation film 338 and theplanarization film 339.

The pixel defining film 344 may be formed to cover the edges of theanode electrode 341 to define a corresponding pixel. The pixel definingfilm 344 may define a plurality of first, second, and third subpixelsPX1, PX2, and PX2. Each of the first, second, and third subpixels PX1,PX2, and PX3 may be a region in which the anode electrode 341, thelight-emitting layer 342, and the cathode electrode 343 are sequentiallystacked and holes from the anode electrode 341 and electrons from thecathode electrode 343 are combined in the light-emitting layer 342 toemit light.

The light-emitting layer 342 may be formed on the anode electrode 341and the pixel defining film 344. The light-emitting layer 342 may be anorganic light-emitting layer. The light-emitting layer 342 may emit bluelight or short-wavelength light such as ultraviolet (UV) light. The peakwavelength range of the blue light may be about 450 nm to 490 nm, andthe peak wavelength range of the UV light may be 450 nm or shorter. Inthis embodiment, the light-emitting layer 342 may be a common layer thatis formed in common for all the first, second, and third subpixels PX1,PX2, and PX3. The display panel 110 may include a light wavelengthconversion layer QDL, which converts the blue light or theshort-wavelength light (such as UV light) emitted by the light-emittinglayer 342 into red light, green light, and blue light. The display panel110 may also include the color filter layer CFL which transmit redlight, green light, and blue light therethrough.

The light-emitting layer 342 may include a hole transport layer, anemission layer, and an electron transport layer. The light-emittinglayer 342 may have a tandem structure with two or more stacks. In thisembodiment, a charge generating layer may be formed between the stacks.

The cathode electrode 343 may be formed on the light-emitting layer 342.The cathode electrode 343 may be formed to cover the light-emittinglayer 342. The cathode electrode 343 may be a common layer formedcommonly for all pixels.

The light-emitting element layer EML may be formed as a topemission-type light-emitting element layer that emits light in adirection toward the second substrate 112, e.g., in an upper direction.In this embodiment, the anode electrode 341 may be formed of a metalmaterial with high reflectance such as a stack of Al and Ti (e.g.,Ti/Al/Ti), a stack of Al and indium tin oxide (ITO) (e.g., ITO/Al/ITO),a silver (Ag)-palladium (Pd)-copper (Cu) (APC) alloy, or a stack of anAPC alloy and ITO (e.g., ITO/APC/ITO). The cathode electrode 343 may beformed of a transparent conductive oxide (TCO) material such as ITO orindium zinc oxide (IZO) that may transmit light therethrough or asemi-transmissive conductive material such as magnesium (Mg), Ag, or analloy thereof. In an embodiment where the cathode electrode 343 isformed of a semi-transmissive conductive material, the emissionefficiency of the light-emitting element layer 304 may be improved dueto a micro-cavity effect.

The TFEL 305 is formed on the light-emitting element layer EML. The TFEL305 prevents oxygen or moisture from infiltrating into thelight-emitting layer 342 and the cathode electrode 343. The TFEL 305 mayinclude at least one inorganic film. The inorganic film may be formed ofsilicon nitride, aluminum nitride, zirconium nitride, titanium nitride,hafnium nitride, tantalum nitride, silicon oxide, aluminum oxide, ortitanium oxide. The TFEL 305 may further include at least one organicfilm. The organic film may have a sufficient thickness to preventforeign particles from entering the light-emitting layer 342 and thecathode electrode 343 through the TFEL 305. The organic film may includeone of epoxy, acrylate, and urethane acrylate.

The color filter layer CFL is disposed on a surface of the secondsubstrate 112 that faces the first substrate 111. The color filter layerCFL may include a black matrix 360 and color filters 370.

The black matrix 360 may be formed on the second substrate 112. Theblack matrix 360 may be disposed to overlap with the pixel defining film344. However, the black matrix may be disposed so that it does notoverlap with the first, second, and third subpixels PX1, PX2, and PX3.The black matrix 360 may include a black pigment or an opaque metalmaterial that may be capable of blocking the transmission of lightwithout transmitting light therethrough.

The color filters 370 may be disposed to overlap with the first, second,and third subpixels PX1, PX2, and PX3. A first color filter 371 may bedisposed to overlap with the first subpixel PX1, a second color filter372 may be disposed to overlap with the second subpixel PX2, and a thirdcolor filter 373 may be disposed to overlap with the third subpixel PX3.In this embodiment, the first color filter 371 may be a first-colorlight transmitting filter transmitting light of a first color, thesecond color filter 372 may be a second-color light transmitting filtertransmitting light of a second color, and the third color filter 373 maybe a third-color light transmitting filter transmitting light of a thirdcolor. For example, in an exemplary embodiment, the first, second, andthird colors may be red, green, and blue, respectively. However,exemplary embodiments of the present inventive concepts are not limitedthereto. The peak wavelength range of red light passing through thefirst color filter 371 may be about 620 nm to 750 nm. The peakwavelength range of green light passing through the second color filter372 may be about 500 nm to 570 nm. The peak wavelength range of bluelight passing through the third color filter 373 may be about 450 nm to490 nm.

The boundaries between the color filters 370 may overlap with the blackmatrix 360. Accordingly, the black matrix 370 may prevent light emittedfrom the light-emitting layer 342 of one subpixel from entering thecolor filter 370 of another subpixel to cause color mixing.

An overcoat layer may be formed on the color filters 370 in order toplanarize height differences caused by the color filters 370 and theblack matrix 360. However, in certain exemplary embodiments, theovercoat layer may not be provided.

The wavelength conversion layer QDL may be disposed on the color filterlayer CFL. The wavelength conversion layer QDL may include a firstcapping layer 351, a first wavelength conversion layer 352, a secondwavelength conversion layer 353, a third wavelength conversion layer354, a second capping layer 355, an interlayer organic film 356, and athird capping layer 357.

The first capping layer 351 may be disposed on the color filter layerCFL. The first capping layer 351 prevents moisture or oxygen frominfiltrating into the first, second, and third wavelength conversionlayers 352, 353, and 354 through the color filter layer CFL. The firstcapping layer 351 may be formed as an inorganic film using, for example,silicon nitride, aluminum nitride, zirconium nitride, titanium nitride,hafnium nitride, tantalum nitride, silicon oxide, aluminum oxide, ortitanium oxide.

The first, second, and third wavelength conversion layers 352, 353, and354 may be disposed on the first capping layer 351.

The first wavelength conversion layer 352 may be disposed to overlapwith the first subpixel PX1. The first wavelength conversion layer 352may convert the blue Light or the short-wavelength light (such as UVlight) emitted from the light-emitting layer 342 of the first subpixelPX1 into light of the first color. The first wavelength conversion layer352 may include a first base resin, a first wavelength shifter, and afirst scatterer.

The first base resin may be formed of a material having high lighttransmittance and excellent dispersion characteristics for the firstwavelength shifter and the first scatterer. For example, the first baseresin may include an organic material such as an epoxy resin, an acrylicresin, a cardo resin, or an imide resin.

The first wavelength shifter may convert or shift the wavelength ofincident light. In an exemplary embodiment, the first wavelength shiftermay be quantum dots, quantum rods, or a phosphor. In the embodimentwhere the first wavelength shifter is quantum dots, which may be asemiconductor nanocrystal material, the first wavelength shifter mayhave a predetermined band gap depending on the composition and the sizethereof. Therefore, the first wavelength shifter may absorb incidentlight and may then emit light of a predetermined wavelength. The firstwavelength shifter may have a core-shell structure consisting of a coreincluding nanocrystals and a shell surrounding the core. In thisembodiment, examples of the nanocrystals may include group IVnanocrystals, group II-VI compound nanocrystals, group III-V compoundnanocrystals, group IV-VI nanocrystals, or a combination thereof. Theshell may serve as a passivation layer for preventing chemicaldeformation of the core to maintain semiconductor characteristics and/oras a charging layer for imparting the quantum dots electrophoreticcharacteristics. The shell may be a single layer or multilayer film.Examples of the shell may include an oxide of a metal or a non-metal, asemiconductor compound, or a combination thereof.

The first scatterer may have a different refractive index from the firstbase resin and may form an optical interface with the first base resin.For example, the first scatterer may be light-scattering particles. Forexample, the first scatterer may be metal oxide particles such asparticles of titanium oxide (TiO₂), silicon oxide (SiO₂), zirconiumoxide (ZrO₂), aluminum oxide (Al₂O₃), zinc oxide (ZnO), or tin oxide(SnO₂). In another exemplary embodiment, the first scatterer may beorganic particles such as particles of an acrylic resin or a urethaneresin.

The first scatterer may scatter incident light in random directionswithout substantially changing the wavelength of light passing throughthe first wavelength conversion layer 352. In this manner, the path oflight transmitting the first wavelength conversion layer 352 may belengthened, and the color conversion efficiency of the first wavelengthshifter may be improved.

The first wavelength conversion layer 352 may overlap with the firstcolor filter 371. Therefore, some of the blue light or theshort-wavelength light (such as UV light) provided by the first subpixelPX1 may pass through the first wavelength conversion layer 352 as it iswithout being converted into light of the first color by the firstwavelength shifter. However, the blue light or the short-wavelengthlight (such as UV light) incident upon the first color filter 371without being converted by the first wavelength conversion layer 352 maynot be able to pass through the first color filter 371. On the otherhand, the light of the first color obtained by the first wavelengthconversion layer 352 may pass through the first color filter 371 and maybe emitted in the direction toward the second substrate 112.

The second wavelength conversion layer 353 may be disposed to overlapwith the second subpixel PX2. The second wavelength conversion layer 353may convert the blue light or the short-wavelength light (such as UVlight) emitted from the light-emitting layer 342 of the second subpixelPX2 into light of the second color. The second wavelength conversionlayer 353 may include a second base resin, a second wavelength shifter,and a second scatterer. The second base resin, the second wavelengthshifter, and the second scatterer of the second wavelength conversionlayer 353 may be substantially the same as the first base resin, thefirst wavelength shifter, and the first scatterer, respectively, of thefirst wavelength conversion layer 352. Accordingly, detaileddescriptions thereof will be omitted. However, in an embodiment wherethe first and second wavelength shifters are both quantum dots, thediameter of the second wavelength shifter may be smaller than thediameter of the first wavelength shifter.

The second wavelength conversion layer 353 may overlap with the secondcolor filter 372. Therefore, some of the blue light or theshort-wavelength light (such as UV light) provided by the secondsubpixel PX2 may pass through the second wavelength conversion layer 353as it is without being converted into light of the second color by thesecond wavelength shifter. However, the blue light or theshort-wavelength light (such as UV light) incident upon the second colorfilter 372 without being converted by the second wavelength conversionlayer 353 may not be able to pass through the second color filter 372.On the other hand, the light of the second color obtained by the secondwavelength conversion layer 353 may pass through the second color filter372 and may be emitted in the direction toward the second substrate 112.

The third wavelength conversion layer 354 may be disposed to overlapwith the third subpixel PX3. The third wavelength conversion layer 354may convert the blue light or the short-wavelength light (such as UVlight) emitted from the light-emitting layer 342 of the third subpixelPX3 into light of the third color. The third wavelength conversion layer354 may include a third base resin, a third wavelength shifter, and athird scatterer. The third base resin, the third wavelength shifter, andthe third scatterer of the third wavelength conversion layer 354 aresubstantially the same as the first base resin, the first wavelengthshifter, and the first scatterer, respectively, of the first wavelengthconversion layer 352. Accordingly, detailed descriptions thereof will beomitted.

The third wavelength conversion layer 354 may overlap with the thirdcolor filter 373. Therefore, some of the blue light or theshort-wavelength light (such as UV light) provided by the third subpixelPX3 may pass through the third wavelength conversion layer 354 as it isand may then be emitted in the direction toward the second substrate 112through the third color filter 373.

The second capping layer 355 may be disposed on the first, second, andthird wavelength conversion layers 352, 353, and 354 and portions of thefirst capping layer 351 that are exposed without being covered by thefirst, second, and third wavelength conversion layers 352, 353, and 354.The second capping layer 355 prevents moisture or oxygen frominfiltrating into the first, second, and third wavelength conversionlayers 352, 353, and 354. The second capping layer 355 may be formed asan inorganic film using, for example, silicon nitride, aluminum nitride,zirconium nitride, titanium nitride, hafnium nitride, tantalum nitride,silicon oxide, aluminum oxide, or titanium oxide.

The interlayer organic film 356 may be disposed on the second cappinglayer 355. The interlayer organic film 356 may be a planarization layerfor planarizing height differences formed by the first, second, andthird wavelength conversion layers 352, 353, and 354. The interlayerorganic film 356 may be formed as an organic film using an acrylicresin, an epoxy resin, a phenolic resin, a polyamide resin, or apolyimide resin.

The third capping layer 357 may be disposed on the interlayer organicfilm 356. The third capping layer 357 may be formed as an inorganic filmusing, for example, silicon nitride, aluminum nitride, zirconiumnitride, titanium nitride, hafnium nitride, tantalum nitride, siliconoxide, aluminum oxide, or titanium oxide.

The filler member FL may be disposed between the TFEL 305, which isdisposed on the first substrate 111, and the third capping layer 357,which is disposed on the second substrate 112. The filler member FL maybe formed of a material having a buffer function. For example, thefiller member FL may be formed as an organic film using an acrylicresin, an epoxy resin, a phenolic resin, a polyamide resin, or apolyimide resin.

In a non-display area of the display panel 110, an adhesive layer forbonding the first and second substrates 111 and 112 may be disposed, andin a plan view, the filler member FL may be surrounded by the adhesivelayer.

According to the exemplary embodiment of the present inventive conceptsshown in FIG. 4, the first, second, and third subpixels PX1, PX2, andPX3 may emit blue light or short-wavelength light such as UV light. Thelight from the first subpixel PX1 may be converted into light of thefirst color through the first wavelength conversion layer 352 and maythen be output through the first color filter CF1. Light from the secondsubpixel PX2 may be converted into light of the second color through thesecond wavelength conversion layer 353 and may then be output throughthe second color filter CF2. The light from the third subpixel PX3 maybe output through the third wavelength conversion layer 354 and thethird color filter CF3. Accordingly, white light may be output.

Also, according to the exemplary embodiment shown in FIG. 4, since thefirst, second, and third subpixels PX1, PX2, and PX3 are driven in a topemission manner and emit light in the direction toward the secondsubstrate 112, a first heat dissipation film including an opaquematerial such as graphite or Al may be disposed on the first substrate111.

FIG. 5 is a bottom view illustrating an exemplary display device withflexible films thereof that are not bent. FIG. 6 is a bottom viewillustrating an exemplary display device with flexible films that arebent. It is noted that display devices 10 are shown reversed in FIGS. 5and 6, which are bottom views, as compared to the display device 10 ofFIGS. 1 and 2.

Referring to FIGS. 5 and 6, a first sound generator 210 may be connectedto a control circuit board 160 via first and second sound wires WL1 andWL2. For example, in an embodiment in which flexible films 122 are benttoward the bottom surface of a first heat dissipation film 130, asillustrated in FIG. 6, a control circuit board 160 may be disposed onthe bottom surface of the first heat dissipation film 130. The first andsecond sound wires WL1 and WL2 may electrically connect the controlcircuit board 160 and the first sound generator 210. As a result, thefirst sound generator 210 may be configured to receive a first drivingvoltage via the first sound wire WL1 and may receive a second drivingvoltage via the second sound wire WL2. Accordingly, the first soundgenerator 210 may output a first sound by causing a display panel 110 tovibrate in accordance with the first and second driving voltages.

Meanwhile, the display device 10 may further include a sound drivingcircuit outputting the first and second driving voltages in accordancewith sound control signals, which may be digital signals input from asystem-on-chip. The first and second driving voltages may be alternatingcurrent (AC) voltages that swing between a positive level and a negativelevel with respect to a predetermined reference level.

The sound driving circuit may be formed as an IC and may then beattached on the control circuit board 160 or a system board. The sounddriving circuit may include a digital signal processor (DSP) thatprocesses the sound control signals, which may be digital signals, adigital-to-analog converter (DAC) that converts the sound controlsignals processed by the DSP into the first and second driving voltages,which may be analog signals, and an amplifier (AMP) that amplifies andoutputs the analog signals output by the DAC.

FIGS. 5 and 6 illustrate that the first sound generator 210 may bedisposed close to the center of the display panel 110. However,exemplary embodiments of the present inventive concepts are not limitedthereto.

Referring to FIGS. 7 and 8, a first sound generator 210 may be anexciter configured to generate a magnetic force using a voice coil andthereby causes a display panel 110 to vibrate. In this embodiment, thefirst sound generator 210 may include a magnet 211, a bobbin 212, avoice coil 213, and dampers 214.

The magnet 211 may be a permanent magnet, and a sintered magnet such asa barium ferrite magnet may be used. In an exemplary embodiment, themagnet 211 may be formed as a ferric trioxide (Fe₂O₃) magnet, a bariumcarbonate (BaCO₃) magnet, a neodymium magnet, a strontium ferrite magnetwith an improved magnetic component, or an Al, nickel (Ni), or cobalt(Co) cast alloy magnet. However, the exemplary embodiment of the presentinventive concepts are not limited thereto. The neodymium magnet may be,for example, a neodymium-iron-boron (Nd—Fe—B) magnet.

The magnet 211 may include a plate 211 a, a central protruding part 211b that protrudes from the center of the plate 211 a, and a sidewall part211 c protruding from the edge of the plate. The central protruding part211 b and the sidewall part 211 c may be a predetermined distance apartfrom each other. As a result, a predetermined space may be formedbetween the central protruding part 211 b and the sidewall part 211 c.For example, the magnet 211 may have a cylindrical shape. The magnet 211may be in the shape of a cylinder with a circular space formed at one ofthe bases thereof. The plate 211 a of the magnet 211 may be fixed to thelower cover 102 of FIG. 2.

The central protruding part 211 b of the magnet 211 may have N-polemagnetism, and the plate 211 a and the sidewall part 211 c may haveS-pole magnetism. As a result, an external magnetic field may be formedbetween the central protruding part 211 b and the plate 211 a of themagnet 211 and between the central protruding part and the sidewall part211 c of the magnet 211.

The bobbin 212 may be formed into a cylindrical shape. The centralprotruding part 211 b of the magnet 211 may be disposed in the bobbin212. The bobbin 212 may be disposed to surround the central protrudingpart 211 b of the magnet 211. The sidewall part 211 c of the magnet 211may be disposed on the outside of the bobbin 212. For example, thesidewall part 211 c of the magnet 211 may be disposed to surround thebobbin 212. Spaces may be formed between the bobbin 212 and the centralprotruding part 211 b of the magnet 211 and between the bobbin 212 andthe sidewall part 211 c of the magnet 211.

In an exemplary embodiment, the bobbin 212 may be formed of apulp-processed or paper-processed material, Al, Mg, or an alloy thereof,a synthetic resin such as polypropylene, or polyamide-based fibers. Oneend of the bobbin 212 may be attached to a first heat dissipation film130 via an adhesive member. The adhesive member may be a double-sidedtape.

The voice coil 213 may be wound around the outer circumferential surfaceof the bobbin 212. One end of the voice coil 213 adjacent to one end ofthe bobbin 212 may be connected to a first sound wire WL1, and the otherend of the voice coil 213 adjacent to the other end of the bobbin 212may be connected to a second sound wire WL2. As a result, a current mayflow in the voice coil 213 in accordance with first and second drivingvoltages applied to the first and second sound wires WL1 and WL2,respectively. An applied magnetic field may be formed around the voicecoil 213 depending on the current that flows in the voice coil 213. Forexample, the direction of the current that flows in the voice coil 213when the first driving voltage is a positive voltage and the seconddriving voltage is a negative voltage may be opposite to the directionof the current that flows in the voice coil 213 when the first drivingvoltage is a negative voltage and the second driving voltage is apositive voltage. As the first and second driving voltages arealternately driven, the N pole and the S pole of the applied magneticfield may be changed so that an attracting force and a repulsive forcecan be alternately acted upon the magnet 211 and the voice coil 213.Accordingly, the bobbin 212, which has the voice coil 213 woundtherearound may be configured to reciprocate in a third direction (e.g.,a Z-axis direction), as illustrated in FIGS. 9A and 9B. As a result, thedisplay panel 110 and the first heat dissipation film 130 may vibrate inthe third direction (e.g., the Z-axis direction), and first sound may beoutput.

The dampers 214 may be disposed between the top of the bobbin 212 andthe sidewall part 211 c of the magnet 211. The dampers 214 may contractor expand in accordance with the vertical movement of the bobbin 212 andmay thus control the vertical vibration of the bobbin 212. Since thedampers 214 are connected between the bobbin 212 and the sidewall part211 c of the magnet 211, the vertical movement of the bobbin 212 (e.g.,in the Z-axis direction) may be limited by the restoring force of thedampers 214. For example, when the bobbin 212 vibrates above or below apredetermined height, the bobbin bin may return to its original locationdue to the restoring force of the dampers 214.

Referring to FIGS. 10 and 11, a first sound generator 210 may be apiezoelectric element that is configured to contract or expand inaccordance with a voltage applied thereto and thereby causes a displaypanel 110 to vibrate. In this embodiment, the first sound generator 210may include a vibration layer 511, a first electrode 512, a secondelectrode 513, a first pad electrode 512 a, and a second pad electrode513 a.

The first electrode 512 may include a first stem electrode 5121 andfirst branch electrodes 5122. The first stem electrode 5121 may bedisposed on one side of the vibration layer 511 or may be disposed onmore than one side of the vibration layer 511, as illustrated in FIGS.10 and 11. The first stem electrode 5121 may be disposed on the topsurface of the vibration layer 511. The first branch electrodes 5122 maybe branched off from the first stem electrode 5121. The first branchelectrodes 5122 may be disposed in parallel to one another.

The second electrode 513 may include a second stem electrode 5131 andsecond branch electrodes 5132. The second stem electrode 5131 may bedisposed on one side of the vibration layer 511 or may be disposed onmore than one side of the vibration layer 511, as illustrated in FIGS.10 and 11. Referring to FIGS. 10 and 11, the first stem electrode 5121may be disposed on one of the sides of the vibration layer 511 where thesecond stem electrode 5131 is not disposed. The second stem electrode5131 may be disposed on the top surface of the vibration layer 511. Thefirst and second stem electrodes 5121 and 5131 may not overlap with eachother. The second branch electrodes 5132 may be branched off from thesecond stem electrode 5131. The second branch electrodes 5132 may bedisposed in parallel to one another.

The first branch electrodes 5122 and the second branch electrodes 5132may be disposed in parallel to one another in a horizontal direction(e.g., an X- or Y-axis direction). The first branch electrodes 5122 andthe second branch electrodes 5132 may be alternately disposed in avertical direction (e.g., a Z-axis direction). The first branchelectrodes 5122 and the second branch electrodes 5132 may be disposedrepeatedly in the order of a first branch electrode 5122, a secondbranch electrode 5132, a first branch electrode 5122, and a secondbranch electrode 5132 along the vertical direction (e.g., the Z-axisdirection).

The first pad electrode 512 a may be connected to the first electrode512. The first pad electrode 512 a may protrude outwardly from the firststem electrode 5121, which is disposed on one side of the vibrationlayer 511. The second pad electrode 513 a may be connected to the secondelectrode 513. The second pad electrode 513 a may protrude outwardlyfrom the second stem electrode 5131, which is disposed on the other sideof the vibration layer 511. The first and second pad electrodes 512 aand 513 a may protrude outwardly from the first and second stemelectrodes 5121 and 5131 that are disposed on the same side of thevibration layer 511.

The first and second pad electrodes 512 a and 513 a may be connected tolead lines or pad electrodes of a first FPCB. The lead lines or the padelectrodes of the first FPCB may be disposed on the bottom surface of afirst sound circuit board.

The vibration layer 511 may be a piezoelectric actuator that is deformedby first and second driving voltages applied to the first and secondelectrodes 512 and 513, respectively. In this embodiment, the vibrationlayer 511 may be one of a piezoelectric material such as apolyvinylidene difluoride (PVDF) film or lead zirconate titanate (PZT)and an electroactive polymer.

Since the vibration layer 511 is fabricated at high temperature, thefirst and second electrodes 512 and 513 may be formed of a metal with ahigh melting point such as Ag or an alloy of Ag and Pd. In a case wherethe first and second electrodes 512 and 513 are formed of an alloy of Agand Pd, the Ag content of the alloy of Ag and Pd may be greater than thePd content of the alloy of Ag and Pd to raise the melting point of thefirst and second electrodes 512 and 513.

The vibration layer 511 may be disposed between the first branchelectrodes 5122 and the second branch electrodes 5132. The vibrationlayer 511 may contract or expand depending on the difference between thefirst driving voltage applied to the first branch electrodes 5122 andthe second driving voltage applied to the second branch electrodes 5132.

As illustrated in FIG. 11, the polarity of the vibration layer 511between the first branch electrodes 5122 and their respective underlyingsecond branch electrodes 5132 may have an upward direction (↑). In thiscase, the vibration layer 511 may have a positive polarity in upperparts thereof adjacent to the first branch electrodes 5122 and anegative polarity in lower parts thereof adjacent to the second branchelectrodes 5132. Alternatively, the polarity of the vibration layer 511between the second branch electrodes 5132 and their respectiveunderlying first branch electrodes 5122 may have a downward direction(↓). In this case, the vibration layer 511 may have a negative polarityin the upper parts thereof adjacent to the first branch electrodes 5122and a positive polarity in the lower parts thereof adjacent to thesecond branch electrodes 5132. The direction of the polarity of thevibration layer 511 may be determined by a poling process for applyingan electric field to the vibration layer 511 using the first branchelectrodes 5122 and the second branch electrodes 5132.

When the direction of the polarity of the vibration layer 511 betweenthe first branch electrodes 5122 and their respective underlying secondbranch electrodes 5132 is the upward direction (↑), as illustrated inFIG. 12, the vibration layer 511 may contract in accordance with a firstforce F1 in response to a positive first driving voltage and a negativesecond driving voltage being applied to the first branch electrodes 5122and the second branch electrodes 5132, respectively. The first force F1may be a contraction force. On the other hand, in response to a negativefirst driving voltage and a positive second driving voltage beingapplied to the first branch electrodes 5122 and the second branchelectrodes 5132, respectively, the vibration layer 511 may expand inaccordance with a second force F2. The second force F2 may be anextension force.

When the direction of the polarity of the vibration layer 511 betweenthe second branch electrodes 5132 and their respective underlying firstbranch electrodes 5122 is the downward direction (↓), the vibrationlayer 511 may expand in accordance with an extension force in responseto a positive first driving voltage and a negative second drivingvoltage being applied to the first branch electrodes 5122 and the secondbranch electrodes 5132, respectively. On the other hand, in response toa negative first driving voltage and a positive second driving voltagebeing applied to the first branch electrodes 5122 and the second branchelectrodes 5132, respectively, the vibration layer 511 may contract inaccordance with a contraction force. The second force F2 may be anextension force.

According to the embodiment of FIGS. 10 and 11, in a case where thefirst and second driving voltages applied to the first and secondelectrodes 512 and 513, respectively, alternately change from a positivepolarity to a negative polarity, the vibration layer 511 repeatedlycontracts and expands. As a result, the first sound generator 210vibrates.

Since the first sound generator 210 is disposed on the bottom surface ofthe display panel 110, the display panel 110 may vibrate vertically dueto stress, as illustrated in FIGS. 13A and 13B, as the vibration layer511 of the first sound generator 210 contracts and expands. Since thefirst sound generator 210 causes the display panel 110 to vibrate, thedisplay device 10 may be configured to output sound.

FIG. 14 is a bottom view of a display device according to anotherexemplary embodiment of the present disclosure. It is noted that adisplay device 10 is shown reversed in FIG. 14, which is a bottom view,as compared to the display device 10 of FIGS. 1 and 2.

The embodiment of FIG. 14 differs from the embodiments of FIGS. 1through 6 in that the display device 10 includes two sound generators(210 and 220). The embodiment of FIG. 14 will hereinafter be described,focusing mainly on the difference(s) with the embodiments of FIGS. 1through 6.

Referring to FIG. 14, first and second sound generators 210 and 220 maybe exciters that are configured to generate a magnetic force using avoice coil which causes a display panel 110 to vibrate, as illustratedin FIGS. 7 and 8. The first and second sound generators 210, 220 mayalso be piezoelectric elements contracting and expanding in accordancewith a voltage applied thereto and thereby causing the display panel 110to vibrate, as illustrated in FIGS. 10 and 11. The first and secondsound generators 210 and 220 may both serve as tweeters for outputtingsound having a high sound pressure level in a high-frequency range. Thehigh-frequency range may be a range of frequencies of 1 kHz or higher,as illustrated in FIG. 19.

In an exemplary embodiment, the first sound generator 210 may bedisposed adjacent to the right side of the display panel 110, and thesecond sound generator 220 may be disposed adjacent to the left side ofthe display panel 110. Accordingly, the first sound generator 210 may beconfigured to output a first sound to the right front of the displaypanel 110, and the second sound generator 220 may be configured tooutput a second sound to the left front of the display panel 110.Therefore, the display device 10 may provide stereo sound of 2.0channels to a user.

The fundamental zero (F0) of each of the first and second soundgenerators 210 and 220 may be 1 kHz or higher. Here, F0 denotes theminimum frequency at which the displacement of vibration of the displaypanel 110 exceeds a reference displacement level due to each soundgenerator. If the displacement of vibration of the display panel 110exceeds the reference displacement level due to each sound generator,the sound pressure level of each sound generator may become higher thana reference sound pressure level.

The sound output characteristics of the first sound generator 210 andthe sound output characteristics of the second sound generator 220 maybe substantially the same. For example, the F0 of the first soundgenerator 210 and the F0 of the second sound generator 220 may besubstantially the same, and the sound pressure level, at each frequency,of the first sound generator 210 and the sound pressure level, at eachfrequency, of the second sound generator 220 may be one of T1, T2, T3,and T4 of FIG. 19. Referring to FIG. 19, T1, T2, T3, and T4 may all havea F0 in a high-frequency range HFR but have different sound pressurelevels in a low-frequency range LFR. The sound pressure level in thelow-frequency range LFR may gradually decrease from T1 to T4. In anembodiment where the display device 10 provides stereo sound of 2.0channels to the user using the first and second sound generators 210 and220, the sound pressure level, at each frequency, of the first soundgenerator 210 and the sound pressure level, at each frequency, of thesecond sound generator 220 may preferably be Ti or T2, which has a highsound pressure level even in the low-frequency range LFR, because thereis no woofer for outputting low-pitched sound.

Alternatively, the sound output characteristics of the first soundgenerator 210 may be different from the sound output characteristics ofthe second sound generator 220. For example, the sound pressure level,at each frequency, of the first sound generator 210 may be differentfrom the sound pressure level, at each frequency, of the second soundgenerator 220. Specifically, if the sound pressure level, at eachfrequency, of the first sound generator 210 is one of T1, T2, T3, and T4of FIG. 19, the sound pressure level, at each frequency, of the secondsound generator 220 may be another one of T1, T2, T3, and T4 of FIG. 19.

For example, the F0 of the first sound generator 210 may be differentfrom the F0 of the second sound generator 220. In an exemplaryembodiment, the F0 of the first sound generator 210 may be higher thanthe F0 of the second sound generator 220. In an embodiment where thefirst and second sound generators 210 and 220 are exciters generating amagnetic force using a voice coil and thereby causing the display panel110 to vibrate, the F0 of each of the first and second sound generators210 and 220 may decrease as the diameter of the bobbin 212 of each ofthe first and second sound generators 210 and 220 increases. Thus, thediameter of the bobbin 212 of the first sound generator 210 may besmaller than the diameter of the bobbin 212 of the second soundgenerator 220. In an embodiment where the first and second soundgenerators 210 and 220 are piezoelectric elements contracting andexpanding in accordance with a voltage applied thereto and therebycausing the display panel 110 to vibrate, the F0 of each of the firstand second sound generators 210 and 220 may decrease as the area of thevibration layer 511 of each of the first and second sound generators 210and 220 increases. Accordingly, the area of the vibration layer 511 ofthe first sound generator 210 may be smaller than the area of thevibration layer 511 of the second sound generator 220.

In the embodiment of FIG. 14, the first sound generator 210 may bedisposed adjacent to one side of the display panel 110, the second soundgenerator 220 may be disposed adjacent to the other side of the displaypanel 110, and sound having a high sound pressure level in ahigh-frequency range is output using the first and second soundgenerators 210 and 220. Therefore, the display device 10 may providestereo sound of 2.0 channels to the user.

FIG. 15 is a bottom view of a display device according to anotherexemplary embodiment of the present disclosure. It is noted that adisplay device 10 is shown reversed in FIG. 15, which is a bottom view,as compared to the display device 10 of FIGS. 1 and 2.

The embodiment of FIG. 15 differs from the embodiments of FIGS. 1through 6 in that the display device 10 includes three sound generators(210, 220, and 230). The embodiment of FIG. 15 will hereinafter bedescribed, focusing mainly on the difference(s) with the embodiments ofFIGS. 1 through 6.

Referring to FIG. 15, first, second, and third sound generators 210,220, and 230 may be exciters that are configured to generate a magneticforce using a voice coil and thereby causes a display panel 110 tovibrate, as illustrated in FIGS. 7 and 8. The first, second and thirdsound generators may also be piezoelectric elements contracting andexpanding in accordance with a voltage applied thereto and therebycausing the display panel 110 to vibrate, as illustrated in FIGS. 10 and11. In this embodiment, the first, second, and third sound generators210, 220, and 230 may all serve as tweeters for outputting sound havinga high sound pressure level in a high-frequency range. Thehigh-frequency range may be a range of frequencies of 1 kHz or higher,as illustrated in FIG. 19.

The first sound generator 210 may be disposed adjacent to the center ofthe display panel 110, the second sound generator 220 may be disposedadjacent to the right side of the display panel 110, the third soundgenerator 230 may be disposed adjacent to the left side of the displaypanel 110. Accordingly, the first sound generator 210 may be configuredto output a first sound to the central front of the display panel 110,the second sound generator 220 may be configured to output a secondsound to the right front of the display panel 110, and the third soundgenerator 230 may be configured to output a third sound to the leftfront of the display panel 110. Therefore, the display device 10 may beconfigured to provide stereo sound of 3.0 channels to a user.

The F0 of each of the first, second, and third sound generators 210,220, and 230 may be 1 kHz or higher. The sound pressure level at eachrespective frequency of the first sound generator 210, the second soundgenerator 220, and the third sound generator 230 may all besubstantially the same. For example, the F0 of the first sound generator210, the F0 of the second sound generator 220, and the F0 of the thirdsound generator 230 may all be substantially the same, and the soundpressure level, at each respective frequency, of the first soundgenerator 210, the second sound generator 220, and the third soundgenerator 230 may be one of T1, T2, T3, and T4 of FIG. 19. In anembodiment where the display device 10 is configured to provide stereosound of 3.0 channels to the user using the first, second, and thirdsound generators 210, 220, and 230, the sound pressure level, at eachfrequency, of the first sound generator 210, the second sound generator220 and the third sound generator 230 may preferably be T1 or T2, whichhas a high sound pressure level even in the low-frequency range LFR,because there is no woofer for outputting low-pitched sound.

Alternatively, the sound output characteristics of the first soundgenerator 210, the sound output characteristics of the second soundgenerator 220, and the sound output characteristics of the third soundgenerator 230 may differ. For example, the sound pressure level, at eachrespective frequency, of the first sound generator 210, the second soundgenerator 220, and the third sound generator 230 may differ. If thesound pressure level, at each frequency, of the first sound generator210, which is disposed adjacent to the center of the display panel 110,is one of T1, T2, T3, and T4 of FIG. 19, the sound pressure level, ateach frequency, of the second sound generator 220 may be another one ofT1, T2, T3, and T4 of FIG. 19, and the sound pressure level, at eachfrequency, of the third sound generator 230 may be yet another one ofT1, T2, T3, and T4 of FIG. 19. In another example, the sound pressurelevel, at each respective frequency, of the first sound generator 210,the second sound generator 220, and the third sound generator 230 mayall differ.

For example, the F0 of the first sound generator 210 may be differentfrom the F0 of the second sound generator 220. The F0 of the first soundgenerator 210, which is disposed adjacent to the center of the displaypanel 110, may be higher than the F0 of each of the second and thirdsound generators 220 and 230. In an embodiment where the first, second,and third sound generators 210, 220, and 230 are exciters configured togenerate a magnetic force using a voice coil and thereby causing thedisplay panel 110 to vibrate, the F0 of each of the first, second, andthird sound generators 210, 220, and 230 decreases as the diameter ofthe bobbin 212 of each of the first, second, and third sound generators210, 220, and 230 increases. Thus, the diameter of the bobbin 212 of thefirst sound generator 210 may be smaller than the diameter of the bobbin212 of each of the second and third sound generators 220 and 230. In anembodiment where the first, second, and third sound generators 210, 220,and 230 are piezoelectric elements contracting and expanding inaccordance with a voltage applied thereto and thereby causing thedisplay panel 110 to vibrate, the F0 of each of the first, second, andthird sound generators 210, 220, and 230 decreases as the area of thevibration layer 511 of each of the first, second, and third soundgenerators 210, 220, and 230 increases. Accordingly, the area of thevibration layer 511 of the first sound generator 210 may be smaller thanthe area of the vibration layer 511 of each of the second and thirdsound generators 220 and 230.

In the embodiment of FIG. 15, the first sound generator 210 may bedisposed adjacent to the center of the display panel 110, the secondsound generator 220 may be disposed adjacent to one side of the displaypanel 110, the third sound generator 230 may be disposed adjacent to theother side of the display panel 110. Sound having a high sound pressurelevel in a high-frequency range may be output using the first, second,and third sound generators 210, 220, and 230. Therefore, the displaydevice 10 may provide stereo sound of 3.0 channels to the user.

FIGS. 16A and 16B are a side view and a bottom view, respectively, of adisplay device according to another exemplary embodiment of the presentdisclosure. It is noted that a display device 10 is shown reversed ineach of FIGS. 16A and 16B, which are bottom views, as compared to thedisplay device 10 of FIGS. 1 and 2.

The exemplary embodiment of FIGS. 16A and 16B differ from theembodiments of FIGS. 1 through 6 in that the display device 10 includesthree sound generators (210, 220, and 240). The exemplary embodiment ofFIGS. 16A and 16B will hereinafter be described, focusing mainly on thedifference(s) with the embodiments of FIGS. 1 through 6.

Referring to FIGS. 16A and 16B, first and second sound generators 210and 220 may be exciters configured to generate a magnetic force using avoice coil and thereby causing a display panel 110 to vibrate, asillustrated in FIGS. 7 and 8. The first and second sound generators mayalternatively be piezoelectric elements that are configured to contractand expand in accordance with a voltage applied thereto and therebycausing the display panel 110 to vibrate, as illustrated in FIGS. 10 and11. A fourth sound generator 240 may be an exciter configured togenerate a magnetic force using a voice coil and thereby causing thedisplay panel 110 to vibrate, as illustrated in FIGS. 7 and 8, thefourth sound generator 240 may alternatively be a linear resonantactuator (LRA) or an eccentric rotating mass (ERM) generating a magneticforce using a voice coil and thereby causing the display panel 110 tovibrate, as illustrated in FIG. 17.

In an embodiment where the fourth sound generator 240 is an exciterconfigured to generate a magnetic force using a voice coil and therebycausing the display panel 110 to vibrate, as illustrated in FIGS. 7 and8, the F0 of each of the first, second, and fourth sound generators 210,220, and 240 may decrease as the diameter of the bobbin 212 of each ofthe first, second, and fourth sound generators 210, 220, and 240increases. Thus, the diameter of the bobbin 212 of the fourth soundgenerator 240 may be greater than the diameter of the bobbin 212 of eachof the first and second sound generators 210 and 220.

In an embodiment where the fourth sound generator 240 is an LRA, asillustrated in FIG. 17, the fourth sound generator 240 may include alower chassis 610, an FPCB 620, a voice coil 630, a magnet 640, a spring650, and an upper chassis 660. The lower and upper chassis 610 and 660may be formed of a metal material. The FPCB 620 may be disposed on asurface of the lower chassis 610 that faces the upper chassis 660 andmay be connected to first and second sound wires WL1 and WL2. The voicecoil 630 may be connected to a surface of the FPCB 620 that faces theupper chassis 660. Accordingly, one end of the voice coil 630 may beelectrically connected to the first sound wire WL1, and the other end ofthe voice coil 630 may be electrically connected to the second soundwire WL2. In an exemplary embodiment, the magnet 640 may be a permanentmagnet, and a voice coil groove 641, in which the voice coil 630 isreceived, may be formed on a surface of the magnet 640 that faces thevoice coil 630. A spring 650 may be disposed between the magnet 640 andthe upper chassis 660.

The direction of a current that flows in the voice coil 630 of thefourth sound generator 240 may be controlled in accordance with firstand second driving voltages applied to the first and second sound wiresWL1 and WL2. An applied magnetic field may be formed around the voicecoil 630 depending on the current that flows in the voice coil 630. Forexample, the direction of the current that flows in the voice coil 630when the first driving voltage is a positive voltage and the seconddriving voltage is a negative voltage may be opposite to the directionof the current that flows in the voice coil 630 when the first drivingvoltage is a negative voltage and the second driving voltage is apositive voltage. As the first and second driving voltages arealternately driven, an attracting force and a repulsive force may beacted upon the magnet 640 and the voice coil 630 so that the magnet 640may be configured to reciprocate between the voice coil 630 and theupper chassis 660 due to the spring 650. As a result, the vibrationsurface disposed on the upper chassis 660 may be configured to vibrate,and a fourth sound may be output.

The first and second sound generators 210 and 220 may serve as tweetersfor outputting sound having a high sound pressure level in ahigh-frequency range. On the other hand, the fourth sound generator 240may serve as a woofer for outputting sound having a high sound pressurelevel in a low-frequency range. The high-frequency range may be a rangeof frequencies of 1 kHz or higher, and the low-frequency range may be arange of frequencies of 800 Hz or lower, as illustrated in FIG. 19.

The first sound generator 210 may be disposed adjacent to the right sideof the display panel 110, and the second sound generator 220 may bedisposed adjacent to the left side of the display panel 110. FIGS. 16Aand 16B illustrate that the fourth sound generator 240 may be disposedadjacent to the upper side of the display panel 110, but the location ofthe fourth sound generator 240 may not be particularly limited becausethe fourth sound generator 240 serves as a woofer with a relativelylower sound directivity than a tweeter. Accordingly, the first soundgenerator 210 may be configured to output first sound to the right frontof the display panel 110. The second sound generator 220 may beconfigured to output second sound to the left front of the display panel110. The fourth sound generator 240 may be configured to output alow-pitched fourth sound. Therefore, the display device 10 may providestereo sound of 2.1 channels to a user.

The F0 of each of the first and second sound generators 210 and 220 maybe 1 kHz or higher. The F0 of the fourth sound generator 240 may be 800Hz or lower, preferably, 400 Hz or lower.

The sound output characteristics of the first sound generator 210 andthe sound output characteristics of the second sound generator 220 maybe substantially the same. For example, the F0 of the first soundgenerator 210 and the F0 of the second sound generator 220 may besubstantially the same, and the sound pressure level, at each frequency,of the first sound generator 210 and the sound pressure level, at eachfrequency, of the second sound generator 220 may be one of T1, T2, T3,and T4 of FIG. 19. Since the display device 10 includes the fourth soundgenerator 240 which is configured to output a low-pitched sound, thesound pressure level, at each frequency, of the first sound generator210 and the sound pressure level, at each frequency, of the second soundgenerator 220 may preferably be T3 or T4 because the first and secondsound generators 210 and 220 do not need to have a high sound pressurelevel in the low-frequency range LFR. The sound pressure level, at eachfrequency, of the fourth sound generator 240 may be one of W1, W2, W3,and W4 of FIG. 19.

Alternatively, the sound output characteristics of the first soundgenerator 210 and the sound output characteristics of the second soundgenerator 220 may differ. For example, the sound pressure level, at eachfrequency, of the first sound generator 210 and the sound pressurelevel, at each frequency, of the second sound generator 220 may differ.For example, the F0 of the first sound generator 210 and the F0 of thesecond sound generator 220 may differ.

In the exemplary embodiment of FIGS. 16A and 16B, sound having a highsound pressure level in a high-frequency range is output using the firstand second sound generators 210 and 220, and sound having a low soundpressure level in a low-frequency range is output using the fourth soundgenerator 240. Accordingly, the display device 10 may provide stereosound of 2.1 channels to the user.

FIG. 18 is a bottom view of a display device according to anotherexemplary embodiment of the present disclosure. It is noted that adisplay device 10 is shown reversed in FIG. 18, which is a bottom view,as compared to the display device 10 of FIGS. 1 and 2.

The embodiment of FIG. 18 differs from the embodiment of FIGS. 16A and16B in that the display device 10 further includes a third soundgenerator 230. The embodiment of FIG. 18 will hereinafter be described,focusing mainly on the difference(s) with the embodiment of FIGS. 16Aand 16B.

Referring to FIG. 18, the third sound generator 230 may be an exciterconfigured to generate a magnetic force using a voice coil and therebycausing a display panel 110 to vibrate, as illustrated in FIGS. 7 and 8.Alternatively, the third sound generator 230 may be a piezoelectricelement configured to contract and expand in accordance with a voltageapplied thereto and thereby causing the display panel 110 to vibrate, asillustrated in FIGS. 10 and 11. The third sound generator 230 may serveas a tweeter for outputting sound having a high sound pressure level ina high-frequency range.

A first sound generator 210 may be disposed adjacent to the center ofthe display panel 110. A second sound generator 220 may be disposedadjacent to the right side of the display panel 110. The third soundgenerator 230 may be disposed adjacent to the left side of the displaypanel 110. Accordingly, the first sound generator may be configured tooutput a first sound to the central front of the display panel 110. Thesecond sound generator may be configured to output a second sound to theright front of the display panel 110. The third sound generator may beconfigured to output a third sound to the left front of the displaypanel 110, and low-pitched fourth sound may be output by the fourthsound generator 240. Therefore, the display device 10 may be configuredto provide stereo sound of 3.1 channels to a user. The F0 of the thirdsound generator 230 may be 1 kHz or higher. The sound outputcharacteristics of the third sound generator 230 may be substantiallythe same as the sound output characteristics of the first soundgenerator 210 and the sound output characteristics of the second soundgenerator 220. For example, the F0 of the first sound generator 210, theF0 of the second sound generator 220, and the F0 of the third soundgenerator 230 may be substantially the same. The sound pressure level,at each respective frequency, of the first sound generator 210, thesecond sound generator 220, and the third sound generator 230 may be oneof T1, T2, T3, and T4 of FIG. 19. Since the display device 10 includesthe fourth sound generator 240 for outputting low-pitched sound, thesound pressure level, at each respective frequency, of the first soundgenerator 210 and the second sound generator 220 may preferably be T3 orT4 because the first and second sound generators 210 and 220 do not needto have a high sound pressure level in the low-frequency range LFR.

Alternatively, the sound output characteristics of the first soundgenerator 210, the second sound generator 220 and the third soundgenerator 230 may differ. For example, the sound pressure level, at eachrespective frequency, of the first sound generator 210, the second soundgenerator 220, and the third sound generator 230 may differ. Forexample, the F0 of the first sound generator 210, the F0 of the secondsound generator 220, and the F0 of the third sound generator 230 maydiffer.

In the exemplary embodiment of FIGS. 16A and 16B, the first and secondsound generators 210 and 220 are configured to output sound having ahigh sound pressure level in a high-frequency range. The fourth soundgenerator 240 is configured to output sound having a low sound pressurelevel in a low-frequency range. Accordingly, the display device 10 maybe configured to provide stereo sound of 3.1 channels to the user.

FIG. 19 is a graph showing the sound pressure levels, at each frequency,of sound generated by sound generators.

Referring to FIG. 19, the X axis represents frequency (Hz), the Y axisrepresents sound pressure level (dB), and W1, W2, W3, and W4 representsound pressure levels, at each frequency, of sound generated by soundgenerators that serve as woofers. The F0 of each of W1, W2, W3, and W4may be within the low-frequency range LFR. The F0 of each of W1, W2, W3,and W4 may be 800 Hz or lower, preferably, 400 Hz or lower. W1, W2, W3,and W4 may gradually decrease at a predetermined slope in amid-frequency range MFR and the high-frequency range HFR. The absolutevalues of the slopes of W1, W2, W3, and W4 in the mid- andhigh-frequency ranges MFR and HFR may be greater from W1 to W2 to W3 toW4. The characteristics of sound generated by each sound generator thatserves as a woofer may be set to one of W1, W2, W3, and W4.

Referring to FIG. 19, T1, T2, T3, and T4 refer to the sound pressurelevels, at each frequency, of sound generated by sound generators thatserve as tweeters. The F0 of each of T1, T2, T3, and T4 may be withinthe high-frequency range HFR. The F0 of each of T1, T2, T3, and T4 maybe 1 kHz or higher. T1, T2, T3, and T4 may gradually increase at apredetermined slope in the low- and mid-frequency ranges LFR and MFR.The absolute values of the slopes of T1, T2, T3, and T4 in the low- andmid-frequency ranges LFR and MFR may be greater from T1 to T2 to T3 toT4. The characteristics of sound generated by each sound generator thatserves as a tweeter may be set to one of T1, T2, T3, and T4.

FIG. 20 is a side view illustrating an exemplary display panel of FIG.2. FIGS. 21A through 21E are bottom views illustrating exemplary bobbinsand exemplary heat dissipation pass holes of exemplary first soundgenerators. FIG. 22 is a cross-sectional view taken along line III-III′of FIG. 21A. For convenience, a magnet 211, a voice coil 213, anddampers 214 of a first sound generator 210 are not illustrated in FIGS.21A through 21E.

The exemplary embodiments of FIGS. 20, 21A through 21E, and 22 differfrom the embodiments of FIGS. 1 through 6 in that heat dissipation passholes PH are formed on a surface of a first heat dissipation film 130where a first sound generator 210 is disposed. The exemplary embodimentsof FIGS. 20, 21A through 21E, and 22 will hereinafter be described,focusing mainly on the differences with the embodiments of FIGS. 1through 6.

Referring to FIGS. 20, 21A through 21E, and 22, heat dissipation passholes PH are formed on a surface of a first heat dissipation film 130where a first sound generator 210 is disposed. The heat dissipation passholes PH may overlap with the edge of the first sound generator 210. Inan embodiment where the first sound generator 210 is an exciterconfigured to generate a magnetic force using a voice coil and therebycausing a display panel 110 to vibrate, the heat dissipation pass holesPH may overlap with a bobbin 212 of the first sound generator 210, asillustrated in FIGS. 21A and 22. In this case, heat generated by a voicecoil 213 wound around the bobbin 212 of the first sound generator 210may be discharged, as indicated by arrows of FIG. 22, instead of beingtrapped inside the bobbin 212. The heat dissipation holes PH may beconfigured to effectively release heat generated by the first soundgenerator 210. Accordingly, the influence of the heat generated by thefirst sound generator 210 on the display panel 110 may be minimized bythe first heat dissipation film 130.

The heat dissipation pass holes PH may be recessed holes formed on thefirst heat dissipation film 130, as illustrated in the exemplaryembodiments shown in FIGS. 20 and 22. However, the present disclosure isnot limited thereto. Alternatively, the heat dissipation pass holes PHmay be through holes penetrating the first heat dissipation film 130, asillustrated in FIG. 23.

In the exemplary embodiment shown in FIG. 21A, two heat dissipation passholes PH are formed. However, exemplary embodiments of the presentinventive concepts are not limited thereto. Alternatively, asillustrated in FIG. 21B, four heat dissipation pass holes PH or eightheat dissipation pass holes PH may be formed on the first heatdissipation film 130. As the number of heat dissipation pass holes PHincreases, the number of paths via which heat generated by the firstsound generator 210 is discharged increases, and as a result, the heatdissipation effect of the first heat dissipation film 130 may beimproved. However, as the number of heat dissipation pass holes PHincreases, the contact area between the first sound generator 210 andthe first heat dissipation film 130 decreases, and as a result, theadhesiveness between the first sound generator 210 and the first heatdissipation film 130 decreases. Accordingly, the number of heatdissipation pass holes PH may be appropriately set in consideration ofheat dissipation efficiency and the adhesiveness between the first soundgenerator 210 and the first heat dissipation film 130.

In the exemplary embodiment shown in FIG. 21A, the heat dissipation passholes PH have a rectangular shape in a plan view. However, exemplaryembodiments of the present inventive concepts are not limited thereto.Alternatively, the heat dissipation pass holes PH may have an ellipticalshape in a plan view, as illustrated in FIG. 21D, or may have ahexagonal shape in a plan view, as illustrated in FIG. 21E. In otheralternative embodiments, the heat dissipation pass holes PH may have acircular shape or a polygonal shape other than a rectangular orhexagonal shape in a plan view.

In the exemplary embodiments of FIGS. 20, 21A through 21E, and 22, theheat dissipation pass holes PH are formed on the first heat dissipationfilm 130 to overlap with the first sound generator 210, and heatgenerated by the first sound generator 210 may be effectively dischargedby the heat dissipation pass holes PH. Accordingly, the influence of theheat generated by the first sound generator 210 on the display panel 110may be minimized by the first heat dissipation film 130.

FIG. 24A is a plan view illustrating an exemplary first sound generatorand an exemplary second heat dissipation film. FIG. 24B is across-sectional view taken along line IV-IV′ of FIG. 24A. The embodimentof FIGS. 24A and 24B differs from the embodiments of FIGS. 1 through 6in that a display device 10 further includes a second heat dissipationfilm 180. The embodiment of FIGS. 24A and 24B will hereinafter bedescribed, focusing mainly on the difference(s) with the embodiments ofFIGS. 1 through 6.

Referring to FIGS. 24A and 24B, the second heat dissipation film 180 maybe disposed on a surface of a first heat dissipation film 130 where afirst sound generator 210 is disposed. In an exemplary embodiment, thesecond heat dissipation film 180 may be formed in one integral body withthe first heat dissipation film 130. However, in alternativeembodiments, the second heat dissipation film 180 may be formedseparately from the first heat dissipation film 130. The first heatdissipation film 130 may be configured to cover an entire firstsubstrate 111, and the second heat dissipation film 180 may be disposedto cover part of the first heat dissipation film 130. For example, thesecond heat dissipation film 180 may overlap with the first soundgenerator 210. In an embodiment where the first sound generator 210 isan exciter configured to generate a magnetic force using a voice coiland thereby causing a display panel 110 to vibrate, the second heatdissipation film 180 may overlap with a bobbin 212 of the first soundgenerator 210, as illustrated in FIG. 24. The second heat dissipationfilm 180 may include a metal layer formed of Cu or Al, a ceramic layerformed of a piezoelectric material, or aerogel. In this embodiment,since heat generated by the first sound generator 210 may be blocked bythe second heat dissipation film 130, the influence of the heatgenerated by the first sound generator 210 on the display panel 110 maybe prevented.

In the exemplary embodiment illustrated in FIG. 24B, the width of a heatdissipation layer 133 of the first heat dissipation film 130 may besmaller than the width of the first sound generator 210. However,exemplary embodiments of the present inventive concepts are not limitedthereto. Alternatively, as illustrated in FIG. 24C, the width of theheat dissipation layer 133 of the first heat dissipation film 130 may begreater than the width of the first sound generator 210.

FIG. 25 is a cross-sectional view illustrating an exemplary first soundgenerator and an exemplary first heat dissipation film. The embodimentof FIG. 25 differs from the embodiments of FIGS. 1 through 6 in that afirst heat dissipation film 130 includes vibration transmission layersin addition to a heat dissipation layer. The embodiment of FIG. 25 willhereinafter be described, focusing mainly on the difference(s) with theembodiments of FIGS. 1 through 6.

Referring to FIG. 25, the first heat dissipation film 130 may include afirst vibration transmission layer 131, a second vibration transmissionlayer 132, and a heat dissipation layer 133.

The heat dissipation layer 133 may be configured to discharge heatgenerated by a first sound generator 210. The heat dissipation layer 133may include a layer of a metal with high thermal conductivity such asgraphite, Ag, Cu, or Al.

The heat dissipation layer 133 may include a plurality of metal layersformed in a first direction (e.g., an X-axis direction) and a seconddirection (e.g., a Y-axis direction), rather than in a third direction(e.g., a Z-axis direction). In this embodiment, heat generated by thevoice coil of the first sound generator 210 may be diffused in the firstdirection (e.g., an X-axis direction) and the second direction (e.g., aY-axis direction) and may be effectively released. Accordingly, theinfluence of heat generated by the first sound generator 210 on adisplay panel 110 may be minimized by the first heat dissipation film130.

The first vibration transmission layer 131 may be disposed on a firstsurface of the heat dissipation layer 133. The second vibrationtransmission layer 132 may be disposed on a second surface of the heatdissipation layer 133. The second surface of the heat dissipation layer133, which is opposite to the first surface of the heat dissipationlayer 133, may face a first substrate 111. The first sound generator 210may be attached on the first vibration transmission layer 131 via anadhesive member such as an adhesive tape. The second vibrationtransmission layer 132 may be attached to the first substrate 111 via anadhesive member such as a pressure sensitive adhesive (PSA).

The first and second vibration transmission layers 131 and 132 may beformed of PI. In an embodiment where the heat dissipation layer 133includes a plurality of metal layers formed in the first and seconddirections (e.g., the X- and Y-axis directions), rather than in thethird direction (e.g., the Z-axis direction), the transmission of thevibration of the first sound generator 210 to the first substrate 111may be reduced due to the heat dissipation layer 133. Therefore, theforce delivered from the first sound generator 210 to the firstsubstrate 111 through the vibration of the first sound generator 210 maybe strengthened when the first heat dissipation film 130 includes thefirst vibration transmission layer 131, the second vibrationtransmission layer 132, and the heat dissipation layer 133, as comparedto when the first heat dissipation film 130 only includes the heatdissipation layer 133. Accordingly, the output of first sound throughthe vibration of the display panel 110 using the first sound generator210 may be facilitated.

The exemplary embodiments of FIGS. 26A, 26B, 27, and 28 differ from theembodiment of FIG. 25 in that a part of a heat dissipation film 133 of afirst heat dissipation film 130 is removed. The exemplary embodiments ofFIGS. 26A, 26B, 27, and 28 will hereinafter be described, focusingmainly on the difference(s) with the embodiment of FIG. 25.

Referring to FIGS. 26A and 26B, a heat dissipation layer 133 does notoverlap with a bobbin 212 of a first sound generator 210. Instead, afirst vibration transmission layer 131 may overlap with the bobbin 212of the first sound generator 210. Specifically, a force delivered fromthe first sound generator 210 to a first substrate 111 may be caused bythe vibration of the bobbin 212. Thus, when the heat dissipation layer133 does not overlap with the bobbin 212 of the first sound generator210, the force delivered from the first sound generator 210 to the firstsubstrate 111 through the vibration of the bobbin 212 may bestrengthened.

FIGS. 26A and 26B illustrate that the heat dissipation layer 133overlaps with a central protruding part 211 b inside the bobbin 212, butthe present disclosure is not limited thereto. Alternatively, the heatdissipation layer 133 may overlap with the bobbin 212 and with thecentral protruding part 211 b inside the bobbin 212. In this embodiment,the first vibration transmission layer 131 may overlap not only with thebobbin 212, but also with the central protruding part 211 b inside thebobbin 212.

Referring to FIG. 28, a heat dissipation layer 133 does not overlap witheither a bobbin 212 of a first sound generator 210 or a centralprotruding part 211 b inside the bobbin 212. Instead, a first vibrationtransmission layer 131 may overlap with the bobbin 212. The first heatdissipation film 130 may be thinner in an area that overlaps with thebobbin 212 than in an area that does not overlap with the bobbin 212.That is, the first heat dissipation film 130 may include a recessed partin the area that overlaps with the bobbin 212. In this embodiment, theforce delivered from the first sound generator 210 to the firstsubstrate 111 through the vibration of the bobbin 212 of the first soundgenerator 210 may be strengthened.

A second heat dissipation film 180 may be disposed on a recessed part ofthe first vibration transmission layer 131. The bobbin 212 of the firstsound generator 210 may be disposed on the second heat dissipation film180. The second heat dissipation film 180 may be a metal layer formed ofCu or Al or a ceramic layer formed of a piezoelectric material. In thisembodiment, since heat generated by the first sound generator 210 may beblocked by the second heat dissipation film 130, the influence of theheat generated by the first sound generator 210 on a display panel 110may be prevented. Also, a force generated by the vibration of the bobbin212 of the first sound generator 210 may be delivered to the firstsubstrate 111 through the second heat dissipation film 180.

The exemplary embodiments of FIGS. 29A and 29B differ from theembodiment of FIG. 28 in that a plurality of sound generators 210 aredisposed on a second heat dissipation film 180. The embodiment of FIGS.29A and 29B will hereinafter be described, focusing mainly on thedifference(s) with the embodiment of FIG. 28.

Referring to FIGS. 29A and 29B, a larger force may be delivered to afirst substrate 111 when multiple sound generators 210 are provided on asecond heat dissipation film 180 than when a single sound generator 210is provided on the second heat dissipation film 180 because of thevibration of multiple bobbins 212 of the multiple sound generators 210.A single sound may be output by causing a display panel 110 to vibrateusing the multiple sound generators 210.

The exemplary embodiments of FIGS. 30A and 30B differ from theembodiments of FIGS. 1 through 6 in that a first heat dissipation film130 is disposed to cover a part of the surface of a first substrate 111,rather than the entire surface of the first substrate 111. The exemplaryembodiment of FIGS. 30A and 30B will hereinafter be described, focusingmainly on the difference(s) with the embodiments of FIGS. 1 through 6.

Referring to FIGS. 30A and 30B, a first heat dissipation film 130 may bedisposed to cover a part of the surface of a first substrate 111, ratherthan the entire surface of the first substrate 111. Since the first heatdissipation film 130 is configured for dissipating heat generated by afirst sound generator 210, the first heat dissipation film 130 mayoverlap with the first sound generator 210. In this embodiment, thewidth, in a first direction (e.g., an X-axis direction), of the firstheat dissipation film 130 may be greater than the width, in the firstdirection (e.g., the X-axis direction), of the first sound generator210, and the width, in a second direction (e.g., a Y-axis direction), ofthe first heat dissipation film 130 may be greater than the width, inthe second direction (e.g., the Y-axis direction), of the first soundgenerator 210.

The exemplary embodiment of FIG. 31 differs from the embodiments ofFIGS. 1 through 6 in that a plurality of heat dissipation films (130 aand 130 b) are disposed to overlap with a plurality of sound generators(210 and 220). The exemplary embodiment of FIG. 31 will hereinafter bedescribed, focusing mainly on the difference(s) with the exemplaryembodiments of FIGS. 1 through 6.

Referring to FIG. 31, first and second heat dissipation films 130 a and130 b may be disposed to cover a part of the surface of a firstsubstrate 111, rather than the entire surface of the first substrate111.

A first sound generator 210 may be disposed adjacent to the right sideof a display panel 110, and a second sound generator 220 may be disposedadjacent to the left side of the display panel 110. Since the first heatdissipation film 130 a is configured to dissipate heat generated by thefirst sound generator 210, the first heat dissipation film 130 a mayoverlap with the first sound generator 210. In this embodiment, thewidth, in a first direction (e.g., an X-axis direction), of the firstheat dissipation film 130 a may be greater than the width, in the firstdirection (e.g., the X-axis direction), of the first sound generator210, and the width, in a second direction (e.g., a Y-axis direction), ofthe first heat dissipation film 130 a may be greater than the width, inthe second direction (e.g., the Y-axis direction), of the first soundgenerator 210.

Since the second heat dissipation film 130 b is configured fordissipating heat generated by the second sound generator 220, the secondheat dissipation film 130 b may overlap with the second sound generator220. In this embodiment, the width, in the first direction (e.g., theX-axis direction), of the second heat dissipation film 130 b may begreater than the width, in the first direction (e.g., the X-axisdirection), of the second sound generator 220, and the width, in thesecond direction (e.g., the Y-axis direction), of the second heatdissipation film 130 b may be greater than the width, in the seconddirection (e.g., the Y-axis direction), of the second sound generator220.

The exemplary embodiment of FIG. 32 differs from the embodiments ofFIGS. 1 through 6 in that a first heat dissipation film 130 may bedisposed to cover a part of the surface of a first substrate 111, ratherthan the entire surface of the first substrate 111. The exemplaryembodiment of FIG. 32 will hereinafter be described, focusing mainly onthe difference(s) with the embodiments of FIGS. 1 through 6.

Referring to FIG. 32, a first sound generator 210 may be disposedadjacent to the right side of a display panel 110, and a second soundgenerator 220 may be disposed adjacent to the left side of the displaypanel 110. Since the first heat dissipation film 130 is for dissipatingheat generated by the first and second sound generators 210 and 220, thefirst heat dissipation film 130 may overlap with the first and secondsound generators 210 and 220. In this embodiment, the width, in a firstdirection (e.g., an X-axis direction), of the first heat dissipationfilm 130 may be greater than the maximum distance, in the firstdirection (e.g., the X-axis direction), between the first and secondsound generators 210 and 220, and the width, in a second direction(e.g., a Y-axis direction), of the first heat dissipation film 130 maybe greater than the width, in the second direction (e.g., the Y-axisdirection), of the first sound generator 210.

Alternatively, the first sound generator 210 may be disposed adjacent tothe upper side of the display panel 110, and the second sound generator220 may be disposed adjacent to the lower side of the display panel 110.In this embodiment, the width, in the first direction (e.g., the X-axisdirection), of the first heat dissipation film 130 may be greater thanthe widths, in the first direction (e.g., the X-axis direction), of thefirst and second sound generators 210 and 220, and the width, in thesecond direction (e.g., the Y-axis direction), of the first heatdissipation film 130 may be greater than the maximum distance, in thesecond direction (e.g., the Y-axis direction), between the first andsecond sound generators 210 and 220 and may also be greater than thewidths, in the second direction (e.g., the Y-axis direction), of thefirst and second sound generators 210 and 220.

FIG. 33 is a bottom view of a display device according to anotherexemplary embodiment of the present disclosure.

The embodiment of FIG. 33 differs from the embodiments of FIGS. 1through 6 in that a first heat dissipation film 130 is disposed to covera part of the surface of a first substrate 111, rather than the entiresurface of the first substrate 111. The embodiment of FIG. 33 willhereinafter be described, focusing mainly on the difference(s) with theembodiments of FIGS. 1 through 6.

Referring to FIG. 33, a first heat dissipation film 130 may be disposedto cover a part of the surface of a first substrate 111, rather than theentire surface of the first substrate 111. Since the first heatdissipation film 130 is for dissipating heat generated by a first soundgenerator 210, the first heat dissipation film 130 may overlap with thefirst sound generator 210. In this embodiment, the width, in a firstdirection (e.g., an X-axis direction), of the first heat dissipationfilm 130 may be greater than the width, in the first direction (e.g.,the X-axis direction), of the first sound generator 210, and the width,in a second direction (e.g., a Y-axis direction), of the first heatdissipation film 130 may be greater than the width, in the seconddirection (e.g., the Y-axis direction), of the first sound generator210.

The first heat dissipation film 130 may include an extended part 130 aextending from an overlapping part that overlaps with the first soundgenerator 210 to a side of a display panel 110. The extended part 130 aof the first heat dissipation film 130 may be in contact with a lowercover 102 (of FIG. 2) on the side of the display panel 110. The lowercover 102 may be disposed not only on the first heat dissipation film130 and the first sound generator 210, but also on the side surfaces ofthe display panel 110.

Specifically, the metal layer of the extended part 130 a of the firstheat dissipation film 130 may be in contact with the metal of the lowercover 102. In this embodiment, a path may be provided via which heatgenerated by the first sound generator 210 may be delivered to the lowercover 102 through the metal layer of the first heat dissipation film130, and as a result, the heat generated by the first sound generator210 may be effectively released. Therefore, the influence of the heatgenerated by the first sound generator 210 on the display panel 110 maybe minimized by the first heat dissipation film 130.

FIG. 33 illustrates that the extended part 130 a of the first heatdissipation film 130 extends toward the upper side of the display panel110, but the exemplary embodiments of the present inventive concepts arenot limited thereto. For example, the extended part 130 a of the firstheat dissipation film 130 may extend toward the lower, left, or rightside of the display panel 110.

While exemplary embodiments are described above, it is not intended thatthese embodiments describe all possible forms of the present inventiveconcepts. Rather, the words used in the specification are words ofdescription rather than limitation, and it is understood that variouschanges may be made without departing from the spirit and scope of theinventive concept of the present disclosure. Additionally, the featuresof various implementing embodiments may be combined to form furtherembodiments of the present disclosure.

What is claimed is:
 1. A display device comprising: a display panelincluding a first substrate and a light-emitting element layer disposedon a first surface of the first substrate; a first sound generatordisposed on a second surface of the first substrate opposite to thefirst surface of the first substrate, the first sound generatorconfigured to vibrate the display panel to output a first sound; a firstheat dissipation film between the first substrate and the first soundgenerator; and a second heat dissipation film between the firstdissipation film and the first sound generator.
 2. The display device ofclaim 1, wherein the first heat dissipation film includes a metal layerformed of graphite, silver, copper, or aluminum.
 3. The display deviceof claim 1, wherein the second heat dissipation film includes a metallayer formed of copper or aluminum, a ceramic layer having apiezoelectric material, or aerogel.
 4. The display device of claim 1,wherein a thickness of the second heat dissipation film is lower than athickness of the first heat dissipation film.
 5. The display device ofclaim 1, wherein the first heat dissipation film is disposed on anentire of the second surface of the first substrate.
 6. The displaydevice of claim 1, wherein the second heat dissipation film is disposedon a portion of the second surface of the first substrate.
 7. Thedisplay device of claim 1, wherein a width of the first sound generatorin one direction is larger than a width of the second heat dissipationfilm in the one direction.
 8. The display device of claim 7, wherein awidth of the first sound generator in one direction is smaller than awidth of the second heat dissipation film in the one direction.
 9. Adisplay device comprising: a display panel including a first substrateand a light-emitting element layer disposed on a first surface of thefirst substrate; a first sound generator disposed on a second surface ofthe first substrate opposite to the first surface of the firstsubstrate, the first sound generator configured to vibrate the displaypanel to output a first sound; and a heat dissipation film between thefirst substrate and the first sound generator, wherein the heatdissipation film includes: a heat dissipation layer; and a firstvibration transmission layer disposed on a first surface of the heatdissipation layer.
 10. The display device of claim 9, wherein the firstvibration transmission layer is between the heat dissipation layer andthe first sound generator.
 11. The display device of claim 9, whereinthe heat dissipation layer includes a metal layer formed of graphite,silver, copper, or aluminum.
 12. The display device of claim 9, whereinthe first vibration transmission layer includes a polyimide.
 13. Thedisplay device of claim 9, wherein the heat dissipation layer does notoverlap the first sound generator.
 14. The display device of claim 9,wherein the first sound generator includes: a bobbin disposed on thefirst surface of the heat dissipation film; a voice coil surrounding thebobbin; and a magnet spaced apart from the bobbin, and wherein the heatdissipation layer does not overlap the bobbin.
 15. The display device ofclaim 14, wherein the heat dissipation film includes a first portionwhich overlaps the first sound generator and a second portion which doesnot overlap the first sound generator, and wherein a thickness of thefirst portion is lower than a thickness of the second portion.
 16. Thedisplay device of claim 15, wherein the heat dissipation film isdisposed at the second portion.
 17. A display device comprising: adisplay panel including a first substrate and a light-emitting elementlayer disposed on a first surface of the first substrate; a first soundgenerator disposed on a second surface of the first substrate oppositeto the first surface of the first substrate, the first sound generatorconfigured to vibrate the display panel to output a first sound; asecond sound generator disposed on the second surface of the firstsubstrate, the second sound generator configured to vibrate the displaypanel to output a second sound; and a first heat dissipation filmbetween the first substrate and the first sound generator.
 18. Thedisplay device of claim 17, wherein the first heat dissipation film isbetween the first substrate and the second sound generator.
 19. Thedisplay device of claim 17, further comprising: a second heatdissipation film between the first substrate and the second soundgenerator.
 20. A display device comprising: a display panel including afirst substrate and a light-emitting element layer disposed on a firstsurface of the first substrate; a first sound generator disposed on asecond surface of the first substrate opposite to the first surface ofthe first substrate, the first sound generator configured to vibrate thedisplay panel to output a first sound; a heat dissipation film betweenthe first substrate and the first sound generator, and wherein the heatdissipation film includes an extended portion which extends toward aside of the display panel.